Metallurgical coal

[JAParticipant @ja]

There are plans to open a mine at Whitehaven to produce metallurgical coal for the steel industry. At present these are being examined by the government and courts of law. Obviously a lot of people are against the mine.

Almost all iron is produced by blast furnaces using carbon as the fuel and reducing agent to remove oxygen from the iron ore. There are other suggested methods using alternative fuels, usually nuclear. When I worked in the steel industry, over 40 years, all these still used carbon as the reducing agent. Coke, from metallurgical coal, is the almost universal source of this carbon although charcoal was used in the past, even recent past.

Some organisations, even respected ones, believe that the money representing the cost of opening this mine and the saving of transport costs (at present metallurgical coal is shipping into the UK) would be better spent developing a carbon neutral method of making iron.

Question – Is this possible?

JA

Edited By JA on 24/07/2021 13:19:09

[JAParticipant @ja]

[Martin KyteParticipant @martinkyte99762]

Presumably the company proposing opening the mine are expecting to get a return on thier investment from the coal they extract (and or convert to coke). They do not have to pay for import alternatives into the UK unless of course it's the Steel Industry opening the mine. Why would they per se be interested in developing new ways of making steel.

It's nonsense to assume that savings in one part of the economy will result in funding some other economically non connected area.

regards Martin

[CalumParticipant @calumgalleitch87969]

The argument the miners are making is that both steel and the coal to produce it are a fungible commodity, which is probably more or less true, and therefore we may as well reap the economic benefit of making it here. An argument I'm not unsympathetic to – mining and foundrying produce stable, well paid employment – but on the other hand we have to decide if we're serious about steering towards a zero-carbon economy or not.

Ultimately I don't think this is a technical decision – it's one to be made by politicians, who we elect to make these kinds of calls (albeit with the best technical advice they can get). Personally I do think there's something to be said for having one eye on the global geopolitical weather; a shooting war between two G8 countries is hardly unthinkable, and in such a situation you don't want to be buying raw material for your tanks and destroyers from the other side of the world.

[SillyOldDufferModerator @sillyoldduffer]

Posted by JA on 24/07/2021 13:16:55:

…

Some organisations, even respected ones, believe that the money representing the cost of opening this mine and the saving of transport costs (at present metallurgical coal is shipping into the UK) would be better spent developing a carbon neutral method of making iron.

Question – Is this possible?

Yes. Iron is a reactive metal and the ore, which comes in many forms, is mainly Oxides and Carbonate, plus many impurities. Steel makers go to considerable trouble to remove unwanted elements, including Silicon, Phosphorous, Manganese, Cobalt, Magnesium, Sulphur, Copper, Nickel and Calcium. However, the main problem is removing Oxygen. This is usually done by reducing the Oxide or Carbonate with Carbon: at high temperatures Oxygen has a higher affinity for Carbon, so Oxygen transfers producing Carbon Monoxide leaving more-or-less pure Iron behind.

Although any Carbon will reduce iron ore, it pays to use high purity coke, which is made from particular types of coal. Early iron-makers used Charcoal made from wood and many miserable failures resulted from using the wron sort of coal.

However, though metallurgical coke is cheap and clean for steel-making, any reducing agent would do, though many of them are toxic and expensive.

Of the likely future methods I guess electrolysis holds most promise. It's already used to make any metal more reactive than Iron such as Aluminium, Magnesium, Sodium, Potassium, Lithium, Scandium and Titanium etc.

About a third of the world's steel is produced electrically by melting scrap. Same job could be done with coke but electricity makes purer steel that's more profitable.

Until recent times Coal was the cheapest way of making Iron and Steel. The cost advantage will fade over the next century or so, but Global Warming is pushing it out too. The world is moving towards 'polluter pays', and burning coal would be expensive if wasn't dumped for free into the atmosphere. Fortunately there are alternatives, though I suspect steel prices will be higher in future.

Most chemical conversions in any direction are possible provided energy is available.

Dave

[duncan webster 1Participant @duncanwebster1]

I got on to my MP about this. As expected he didn't understand the difference between using coal to make iron and burning it in power stations. I think the main reason for the government calling in this application, which had been approved previously, is the COP26 meeting, but as I said to the MP, if the delegates to that can't understand the difference, perhaps the should find some better delegates. In the meantime we will continue to ship coal across the oceans producing more CO2 than we would if we dug it up in the UK, increasing imports when we could be exporting it to Europe.

There may well be a better way, but if it exists it isn't proven at industrial scale, so it won't be available for a long time . What I would question is why we import coal and iron ore to make iron which is then turned into steel, and export vast quantities of scrap steel, some of which which we presumably re-import. Why not just recycle it ourselves?

[J HancockParticipant @jhancock95746]

As I understand it , the Chinese have, or are in the process of buying 'Scunthorpe' . One of the major considerations is access to cheap coal.

"Fine", we said, , " We'll open up a seam in Cumbria".

Now , all that is being thrown away.

And Scunthorpe makes railway lines ………………for HS2 , now a white elephant.

[Ady1Participant @ady1]

Its a climate emergency. Its a climate catastrophe

Global warming is coming to get us, catastrophic warming is inevitable

So how many reservoirs are we building to hold that most precious asset of life, water?

[JAParticipant @ja]

I realise there is a potentially carbon free way to produce iron. All the processes are proven! The thermite process gives molten iron but at present it is usually used for welding. The aluminium needed in the process is produced by electrolysis that uses far more energy than a blast furnace. Hydro-electric schemes were used for generating the electricity but now it is generally by burning natural gas. Most aluminium smelters are close to gas fields, usually in developing countries. Don't even think about wind power.

"We're all doomed".

JA

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JA on 25/07/2021 11:16:24:

[…]

The aluminium needed in the process is produced by electrolysis that uses far more energy than a blast furnace. Hydro-electric schemes were used for generating the electricity but now it is generally by burning natural gas. Most aluminium smelters are close to gas fields, usually in developing countries.

[…]

.

Wylfa seemed like a good idea …

**LINK**

https://en.wikipedia.org/wiki/Anglesey_Aluminium

**LINK**

https://en.wikipedia.org/wiki/Wylfa_nuclear_power_station

MichaelG.

.

P.S. __ I understood that ‘Metallurgical Coal’ is used for making Steel, rather than Iron

https://www.bhp.com/our-businesses/our-commodities/metallurgical-coal/

… is it actually used for both ?

Edited By Michael Gilligan on 25/07/2021 13:43:08

[SillyOldDufferModerator @sillyoldduffer]

Posted by JA on 25/07/2021 11:16:24:

I realise there is a potentially carbon free way to produce iron. All the processes are proven! The thermite process gives molten iron but at present it is usually used for welding. The aluminium needed in the process is produced by electrolysis that uses far more energy than a blast furnace. Hydro-electric schemes were used for generating the electricity but now it is generally by burning natural gas. Most aluminium smelters are close to gas fields, usually in developing countries. Don't even think about wind power.

"We're all doomed".

JA

All true, but the conclusion is suspect. The mistake is assuming things are done in a particular for sacrosanct reasons and there no alternatives.

When I was a lad almost all aluminium was made with green renewable energy, mostly hydroelectric. Norway was good – plenty of rain landing on mountains producing more electricity than the population could use. Back then, most natural gas was flared off because it appeared in remote oil fields and was difficult to transport; it needed a network of expensive pipelines to be laid. The early gas supply situation is very like renewables today: a cheap energy source requiring massive investment to use it.

The gas problem was solved by applying fresh engineering. Today, there are many transcontinental natural gas pipelines and tankers ship compressed gas by sea safely. Result, for the moment, gas is the cheapest way of generating electricity we have – cheaper and cleaner than coal, with other advantages.

But gas is only at a temporary advantage. It's a diminishing fossil fuel with supply is reckoned in decades, not centuries. When the sources dry up, all those expensive pipelines become scrap-metal, and gas ceases to be the cheapest way of generating electricity. At some point Aluminium will switch to something else.

JA suggests wind power isn't the answer, but it could be. Not by expecting a lone local wind-farm to power a smelter, but by connecting the smelter to a multinational power grid fed by multiple different sources. As most UK energy is already imported from abroad, this isn't a fundamental change. The difference is in how energy is collected, transported and managed. Yes, technical challenges, but there are plenty of solutions to them.

Think big, think different! Engineers fix problems. We never give up at the first obstacle or assume the only answers are old school.

Dave

[Oily RagParticipant @oilyrag]

There was also a report a few months ago that coffee grounds could be used as a 'carbon catalyst' in the steel making process, developed by, I believe, a Brazilian University no less! Not sure I want my steel smelling of coffee when I'm machining it though.

So after all those milk bottle tops we saved as kids (remember that?) the new generations will be saving coffee grounds. Problem is most folk use 'instant' coffee which has no connection to a coffee bean and is purely a chemical extract – the reason I only drink tea made with real leaf.

Martin

[duncan webster 1Participant @duncanwebster1]

Carbon is not a catalyst in the iron making process, it is part of the chemical reaction. It combines with the oxygen from the iron ore leaving behind the molten iron, which can then be made into steel. This means that even if we could find enough coffee grounds, we'd still be producing CO2.

The neat trick would be to find a way to use plastics (hydrocarbons) instead of coal. Use the stuff which cannot be recycled, saves digging up coal, and gives the plastic waste a value so it won't be dumped into the rivers/seas

[Oily RagParticipant @oilyrag]

Duncan,

the reason I put 'carbon catalyst' in inverted comma's was because that is how the Times reported it!

In hindsight I should have probably written 'sic' to show it was how the message was reported. It seems you just cannot get the technical journalists these days.

I do like your idea of using plastic though – out of the box thinking there. But what of all the fumes given off by burning plastic? Isn't one of the gasses released formaldehyde?

Martin

[VicParticipant @vic]

I saw this a while ago.

**LINK**

[Michael GilliganParticipant @michaelgilligan61133]

**LINK**

https://www.materials.unsw.edu.au/veena-sahajwalla

[quote]

Veena is renowned for her internationally commercialised EAF ‘green’ steelmaking process that is utilising millions of waste tyres otherwise destined for landfill as a partial replacement for coke.
[/quote]

MichaelG.

[pgk pgkParticipant @pgkpgk17461]

..or for really big thinking change the way we construct stuff: .carbon nanotubes, graphene sheets and large diamonds?
Using atmospheric CO2 to get the pure stuff…?

pgk

[duncan webster 1Participant @duncanwebster1]

More on Michael's link rubber steel Seems you still need coke, but a lot less, and you need a lot of electricity

[Anthony KnightsParticipant @anthonyknights16741]

There is the process of Direct Reduced Iron, where the ore is heated in a reducing atmosphere of Syngas ( a mixture of carbon monoxide and hydrogen ). This still produces carbon dioxide, but if adapted to use only renewable hydrogen, water vapour would result. The only problem then is producing enough green electricity to heat the process and provide the hydrogen.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 25/07/2021 13:38:04:

P.S. __ I understood that ‘Metallurgical Coal’ is used for making Steel, rather than Iron

**LINK**

… is it actually used for both ?

.

Does anyone here know the answer ?

MichaelG.

[Martin KyteParticipant @martinkyte99762]

The way I inderstand it, roughly, is this. At least the

Coke, limestone and ore plus scrap is fed into the top of the blast furnace. The Coke generates the heat for the melt. The limestone dissolves impurities and is skimmed as slag.The carbon dissolves into the iron and acts as a flux. The molten iron is tapped off and fed to a converter (Bessemer maybe) where Oxygen is blown in which burns off the carbon converting what is essentially cast iron into steel.

Thats the basic process, remelting and refining is neccessary for special steels.

So I suppose Metallurgical Coal is used in making bothe Steel and Iron.

I'm fully open to more up to date information so feel free.

regards Martin

[JAParticipant @ja]

Martin

Almost but not quite.

1. Ore, carbon (coke or charcoal) and limestone are loaded into the top of the furnace. Sometime limestone is not included (as at Corby) since the ore contains a lot of it. The limestone is the flux
2. Hot air is blown in at the bottom of the furnace (the air is heated by the exhaust gas from the furnace). Now days the air pressure can be 4 or more atmospheres.
3. Some of the carbon burns to provide heat. There then follows a number of chemical reactions between the carbon, ore, air and limestone resulting in the removal of the oxygen from the iron ore by most of the remaining carbon.
4. The products from the furnace are: Raw cast iron (containing an uncontrolled amount of carbon and other impurities such as sulphur), slag (the remains of the limestone) which was, at Corby, tipped and then quarried for road stone, and blast furnace gas. The gas, nitrogen and carbon monoxide, is washed with water and used as a low calorific value fuel. The more efficient the furnace the lower the carbon monoxide content. The water, after washing, contains nasties such as zinc and cyanides.

This is different from a cupola which is used for remelting iron and steel for casting.

Scrap steel is used in the steel making process where the remaining carbon is burnt out of the raw iron using a jet of oxygen in a separate furnace. This is highly exothermic and scrap is added, usually half way through a blow, to cool everything down. The resulting metal is essentially pure iron. The correct amount of carbon, may be as coke, is then added to give steel of the required composition.

High alloy steels are produced from steel scrap of known provenance (not scrap cars) in specialist furnaces.

JA

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